Corn storage bags showing promise

Last year, with a massive shift to corn contemplated for the South, a big concern was how the crop might be stored. Large storage bags — already used successfully elsewhere in the world — were touted as a potential solution.

But without having used the bags in the South before, the jury was out. Now, a few months after harvest, how has the storage option done? Very well, it turns out.

To monitor the storage bags, Dennis Gardisser and colleagues put in studies in southeast and northeast Arkansas. They also talked to numerous producers “who shared their experiences with the bags,” says the Extension agricultural engineer with the University of Arkansas. “To summarize: I believe these bags will be a very viable alternative for short-term storage.”

Grain needs to be put into bags at a consistent moisture level — market moisture (for corn, 15.5 percent), or below. The higher the moisture when bagged, the greater the potential for damage or degradation of grain quality.

“When grain was put in at 15.5 percent moisture, or less, we found no heating or grain quality issues develop. We did find pockets of grain — maybe more moist loads cut early in the morning — that went into the bag at higher moisture evolved into issues that reduced grain quality in those locations in the bag.”

Interestingly, the moisture in the bags doesn't seem to migrate. In a grain bin, the air movement carries the moisture with it. But in the sealed bags — “and they must be sealed to work properly — there's no such air movement. There's no carrying mechanism. The only way for the moisture to transfer is wicking and that seems slow to occur. Still, we're encouraging bag-users to avoid making the wet pockets.”

The storage bags also need to be monitored regularly. “We've seen a lot of things happen. Dogs get on them and make toe-tracks. Having them walk across the bags isn't a big deal. But where they dig their claws into the sides to get up top, they can damage the bags.”

Rats particularly like the bags and leave large holes. They tear into the bags, burrow deep and make a home where “I imagine they're quite happy.”

Crows have been trouble in some areas of the state. “Crows are smart critters and they seem to like having something to land on. Then, they drop off near the bags. We're encouraging folks not to put the bags next to a tree line. The crows don't seem to bother bags in the open on a turn-row. But they can peck 100 holes a day in the bags easily.”

Coyotes sometimes bother bags placed on turnrows. The bags have a small inch-square plug-in that “the coyotes grab onto with their teeth and then pull the entire apparatus out.”

If he repeats the test, Gardisser, says the bags will be situated so the receptacle is atop the bag. “The coyotes won't be able to reach it quite as easily. We know it was coyotes, incidentally, because the bags get a dust on them. Their paw prints gave them away.”

As for raccoons, when filling the bags, the less grain spilled the better. “It's the same for crows, actually. I encourage growers to clean up spilled grain because that draws coons in. And they'll figure out how to get in the bags.

“If the bags are gathered in a yard, I'd use some electric fence. Those aren't that expensive and can be paid for with the damage a couple of coons can do.”

Gardisser has neither seen nor heard of deer bothering the bags. “What we have seen are some deer hunters. Not everyone is honest and there have been reports from the Game and Fish Commission as well as producers where people — they assume they're hunters — back up a pickup to the bags, make a gaping hole with a pocket knife, fill the bed and drive away. Deer corn rustlers.”

Checking temperatures

To keep from puncturing the bags, Gardisser placed probes at two- and four-foot depths. “We left the thermocouple wires in the bags and, once a week, plugged them into a handheld instrument for readings. We've since plotted those.”

Researchers found after filling the bags, the temperatures inside were the same as air temperature. As the season progressed, the bag temperatures began to cool.

“The 2-foot level cooled faster than the center, which is expected with less insulation.”

Initially, the levels were running at the same temperatures. But it wasn't long before there was a downward slope in the bag temperatures.

“If there's anything causing grain to degrade there's usually a heating process. So we were looking for any temperatures going up. We kept hearing stories about the (aforementioned) pockets being discovered when the bags were being unloaded.

“So we probed and took samples in multiple locations and found no similar issues. But others have. Again, our insistence on the grain being bagged at 15.5 percent moisture, or less, may have made the difference.”

Storage bag users must also deal properly with water. The orientation of the bags “needs to be such that they don't act as a dike. You don't want a lot of water on an uphill slope having to run the full length of the bags. In those circumstances, any pinpricks or holes in the bags will lead to water damage.”

Gardisser has been impressed with the bagging equipment. “It's well thought out. After a guy has filled and emptied the bags a couple of times, the process is pretty slick.

How long can corn confidently be held in the bags? “I'm real comfortable saying two or three months. The neat thing about these storage bags is they allow producers to move into the December/January market window. They're able to hold corn and maximize marketing strategies.”

And using the bags means the combine doesn't have to stop. “Having the ability to take the truck to an elevator and get it unloaded immediately can be a problem. When the crop is ready, it needs to be harvested, not waiting for trucks.”

However, a producer needs to be careful if he stores corn in the bags for four to six months. “We don't have experience with the bags for a longer period. But we know the longer you hold grain in wet, winter months, (the chances for degradation increase).”

The quality coming out of bags that held a seal seems excellent. But the seal must be tight, warns Gardisser.

“One thing we'll recommend to the bag manufacturer is that a small receptacle-friendly opening be fabricated into the bag. I don't know if they'll be able to do that, but a solution is needed. There needs to be a better way to check the bag temperatures. We do the same with cotton modules when we check them for heat.

“There needs to be one of those openings every 10 feet, or so. A producer could then go down the bag with a thermocouple and a small, rigid probe.”